1. Field of the Invention
The invention relates in general to a display method and associated apparatus, and more particularly, to a display method and associated apparatus capable of adjusting display settings of a subtitle region.
2. Description of the Related Art
When playing an optical disk with a display apparatus and an optical disk drive, a display region of the image frames is frequently limited by an actual display size of the display apparatus. Further, a width-height ratio of a panel of the display apparatus (i.e., a screen width-height ratio) also affects visual effects of a user viewing the image frames.
FIG. 1A shows a schematic diagram of a display frame of a common display device. In a common display apparatus, 16:9 is usually selected as the screen width-height ratio as it renders most comfortable visual sensations to the human eyes. Moreover, the 16:9 screen width-height ratio presents more realistic image frames with minimal distortion.
However, when image frames are initially captured and then recorded in a DVD, the 16:9 ratio is rarely adopted as the recording width-height ratio. FIG. 1B shows a schematic diagram of a recording width-height ratio when recording an image frame. In FIG. 1B, a recording width-height ratio 2.37:1 is taken as an example.
Comparing FIGS. 1A and 1B, it is seen that a width and a height of a screen of a common display device are closer, whereas a width and a height for recording an image frame have a greater difference in a way that a recorded image frame appears flatter. Hence, it can be concluded that the recording width-height ratio for recording an image frame does not match a screen width-height ratio that a display device utilizes for displaying the image frame.
Thus, when outputting an image frame by a DVD player to a display device, instead of directly outputting the 2.37:1 image frame to the display device, the DVD player converts the image frame to an output width-height ratio for actually outputting a display frame. The output width-height ratio of the DVD player is a width-height ratio of the display frame output by the DVD player, and usually matches a common screen width-height ratio (16:9).
Comparing FIGS. 1A and 1B, it is also seen that, when the display frame in a screen width-height ratio of 16:9 has a same image width as the image frame having a recording width-height ratio of 2.37:1, the height of the display frame and greater than the height of the image frame.
As a result, when the DVD player displays a 16:9 display frame obtained by adjusting a 2.37:1 recorded image frame, certain parts of the display frame appear blank due to different heights of the frames. That is, a region of the image frame is smaller such that the display frame cannot be entirely filled.
An actual width-height ratio is given as an example for explaining a cause of the unfilled frame.
Assume that an image frame is recorded using a 2.37:1 recording width-height ratio, and a display apparatus conforms a 1080P (1920×1080) standard. Further, when displaying the image frame on the display apparatus, a horizontal resolution maintained at 1920 pixels is desired.
To maintain the horizontal resolution at 1920 pixels as well as to match the 2.37:1 recording width-height ratio, a vertical resolution of approximately 810 (1920/2.37) pixels is required.
As such, the display apparatus displays image data of 1080 pixels in the horizontal direction and image data of only 810 pixels in the vertical direction. That is, the image data of the image frame with respect to the vertical direction is insufficient for the display apparatus. Correspondingly, a playback apparatus such as a DVD player additionally fills black edges to upper and lower sides of the image frame to make up the insufficient image data in the vertical direction.
In other words, comparing a 16:9 output width-height ratio and a 2.37:1 recording width-height ratio, an image frame of the latter appears wider and flatter. To maintain the consistency in the horizontal resolution when a playback apparatus outputs a display frame, black edges need to be filled at upper and lower sides of the image frame to make up insufficient ranges of the image frame.
FIG. 1C shows a schematic diagram of a conventional playback apparatus adjusting a display frame to a 16:9 output width-height ratio. In FIG. 1C, an actual width-height ratio of the blank region (representing an image frame) and a display width-height ratio of a cinema display system are both 2.37:1. Further, a display frame represented by the entire region has a 16:9 output width-height ratio.
When a playback apparatus adopts a 16:9 output width-height ratio, black edges are resulted at upper and lower sides of an image frame due to a greater height. It should be noted that, a playback apparatus such as a DVD player often further utilizes a lower black region as a subtitle region, and jointly provides the image frame and the subtitle region to a display apparatus.
As previously stated, the display frame outputted by a DVD player has a 16:9 output width-height ratio, which is consistent with a screen width-height ratio of the display apparatus in this example. Hence, the image frame actually displayed by a display device is also consistent with the display frame. That is to say, even when the recording width-height ratio does not match the screen width-height ratio of the display apparatus, a common display apparatus is still able to normally display the image frame through conversion provided by the DVD player.
A cinema display system is market-available for rendering a screen width-height ratio of a display apparatus to be more approximate to a recording width-height ratio adopted in film-making.
FIG. 2A shows a schematic diagram of a screen width-height ratio provided by a cinema display system. The screen width-height ratio of the cinema display system is about 2.37:1, which is different from that of a common display apparatus.
As seen from previous descriptions, a current DVD always adjusts a width-height ratio of an image frame. In reality, a current DVD is unable to learn in advance the type of display device and the screen width-height ratio to be applied, and usually supports only a 16:9 width-height ratio output. In other words, when utilizing a cinema display system having a 2.37:1 width-height ratio, a DVD player nonetheless adjusts an output width-height ratio of a display frame to 16:9.
FIG. 2B shows a schematic diagram of a conventional playback apparatus, after adjusting an output width-height ratio of a display frame to 16:9, displaying an image frame in conjunction with a cinema display system. Based on the foregoing descriptions, it is learned that FIG. 2B represents a display frame adjusted by a DVD player. The right side of FIG. 2B is in equivalence to a display frame displayed by a cinema display system having a 2.37:1 screen width-height ratio in FIG. 2A.
The display frame output by the DVD player includes the image frame in a 2.37:1 width-height ratio and black regions at upper and lower sides. The playback apparatus utilizes the lower black region as a subtitle region.
Theoretically, the image frame included in the display frame has a 2.37:1 width-height ratio, and the screen width-height ratio of the cinema display system is also 2.37:1. Thus, the cinema display system may directly and proportionally scale up the image frame for display, as shown by the arrows in FIG. 2B.
Although the method of proportionally scaling up image data of the pixels is distortion-free, such method may derive other issues. In short, the cinema display system properly scales up the image frame but has deficiencies in the presentation of a subtitle region.
FIG. 2C shows a schematic diagram of a subtitle region in a display frame. As previously described, contents of the subtitle region need to be additionally provided when the cinema display system directly and proportionally scales up the 2.37:1 image frame. Thus, as shown in FIG. 2C, in the prior art, for example, the subtitle region may first be extracted from the display frame. As shown in FIG. 2D, the subtitle region and the scaled up display frame may be together displayed. That is, while displaying the image frame, the subtitle region is superimposed on the image frame for display.
As seen from FIG. 2D, although a cinema display system adopting the above approach is distortion-free since the image frame is proportionally scaled up, a part of the image frame is however covered by the subtitle region. As a result, a cinema display system adopting the above approach is incapable of presenting an intact image frame.
Therefore, there is a need for a solution for processing and presenting a subtitle when displaying a display frame by a cinema display system.